Why Do Some Websites Have “www” and Others Don't? — The Origin Story

AI translation notice: This English version was translated from the original Chinese article with AI assistance. Some nuances may differ from the original.

The cover image is a photograph of the world's first web server: the NeXT computer that Tim Berners-Lee used at CERN.

www, meaning the World Wide Web, is a pretty basic concept — even high school teachers have already covered it.

But today, while reading a few blog sites, I suddenly noticed something I had never seriously thought about before: some URLs are www.blahblah.com, while others are just blahblah.com.

Before I looked into it, I assumed every website had a www, and that the browser simply decided those few letters could be left off, so it hid them from us. Today I got curious and did some digging, and it turns out the browser hiding is not the whole story at all. Current technology made www unnecessary a long time ago, and most modern websites have stopped using it too — where it survives, it is mostly a leftover historical habit.

So this post is mainly about the origin of the www prefix; a later one will cover why it disappeared afterward, and how we use domain names today.

First, the technical side: why does www exist at all?

The earliest Internet differed from today's Internet in plenty of infrastructure-level ways, so many of the protocols and features from back then were designed with very different intentions. If we are curious about why www exists, we probably need to start from the very beginning of the Internet.

The Early Internet — 1969

When the earliest Internet — or rather its predecessor, ARPANET (1969) — came into being, it connected the computers of a few universities and research institutes. Each machine had a hostname, registered directly in the centrally maintained HOSTS.TXT (which DNS would later replace).

The intention back then was simple: connect a few machines so they could talk to each other.

Because there were so few machines, the concept of a domain name did not exist yet, and there was no need for an extra layer of indirection. A simple “machine name → address” mapping was enough.

For the specifics of this period, see this article, Internet History Ramblings, Part 7 — ARPANET (the other posts in that series have nothing to do with this one, but they are genuinely fun — I highly recommend reading more of them)

The Arrival of DNS (Domain Names) — 1983

As more and more machines joined, the network had already become something entirely different from what it once was.

On January 1, 1983, every networked host switched from NCP to TCP/IP, an event also known as TCP/IP Flag Day.

All machines dropped support for the old protocol and supported TCP/IP instead, turning the previous “single network, flat, centralized” architecture into a “multi-network, layered, delegable” one. That also met the demand of a growing number of machines joining the network.

As more and more machines joined, the HOSTS.TXT file, previously maintained by hand at a central location, began to balloon. Back when storage was not the cheap, bottomless resource it is today, having every machine store a copy of HOST.TXT became increasingly unrealistic. Even harder to swallow: whenever something on the network changed, an administrator had to recompile the HOST.TXT file and push it to every machine over FTP, which usually happened once or twice a week. That delay, too, was unacceptable.

Later, on November 23, 1983, Paul Mockapetris designed DNS and submitted RFC 882 and RFC 883 (later replaced in 1987 by RFC 1034 / RFC 1035).

Its core ideas can be summed up in a few points:

• A consistent namespace: do not stuff network numbers, addresses, or routing information into names
• Distributed maintenance: the full database cannot be stored centrally; it has to be sharded + cached
• Delegated authority: whoever owns the data controls the update/cache policy
• A general-purpose directory service: not just host addresses, but mailboxes and future unknown record types too

That guaranteed a decentralized distributed system (each organization could manage the naming of its own machines) that made updating the network easy.

The Prerequisite for www

We said earlier that every organization could manage its own machines, and that by allocating domain names for itself, an organization could divide up responsibilities very conveniently.

Although port technology had existed since 1980, allowing one machine to run multiple services, early machines were expensive and short on resources — you could not have a single machine handle both web service and mail service. So the early approach was to run different services on different machines, like this:

ftp.example.com    file transfer
mail.example.com   mail
news.example.com   newsgroups

That came with a number of benefits at the same time:

1. Clear management boundaries — mail was the sysadmin's problem, the Web belonged to the newly formed network team; each side ran its own machines and no one had to take the blame for the other.
2. Fault isolation — if the mail service went down, it could not affect the Web, and vice versa.
3. The DNS design philosophy — the domain name system was a “hostname → IP” mapping from the very start, not a “service name → IP” mapping. You give each machine a name, and you call it whatever service it runs.

So www is essentially just a third-level domain, with no special privileges whatsoever.

The Arrival of www — 1989

In 1989, Tim (the person on the cover) proposed the concept of the World Wide Web at CERN. The point was not to lay down a website prefix and call on everyone to use www as the domain for web service; it was to propose the URL/HTTP/HTML hypertext system, so that documents could link to each other across machines and be published across organizations.

For instance, CERN's first web server used info.cern.ch, not www.cern.ch.

By the end of 1990, Tim had successfully launched the first web server and browser at CERN, proving that the ideas behind the proposal were workable. He wrote the relevant code directly on a NeXT computer and kept that server running in his office. To stop anyone from accidentally shutting the server down, he stuck a label written in red ink onto the computer: “This machine is a server. DO NOT POWER IT DOWN!”

But when the Web joined an existing network as a new service, administrators usually gave it its own hostname. ftp/mail/news and the like were already named after their services, so the Web carried on the pattern with www.

A Little of What Came After — 1990s

The popularity of the www naming may also have had something to do with the release of the Mosaic browser. In 1993, NCSA released Mosaic, the first browser that let the general public look at images and click links. NCSA's own web server was called www.ncsa.uiuc.edu. The bookmarks and sample links built into Mosaic all pointed at that address, so the first thing users around the world saw when they encountered the Web was www.

Then came Yahoo (1994), Amazon (1994), and eBay (1995), the first wave of commercial internet companies, and their new URLs followed the www prefix as well. That is how it became familiar to the general public.

Why www?

So why, out of all these names, www?

Someone once emailed Tim to ask exactly this; you can click the link to see Tim's explanation.

His explanation is quite interesting:

1. www was something he “suggested,” not something he “mandated.”

“It is a convention. I suggested it early on, in this guide...”

He suggested it in a Style Guide (a guide written for webmasters) — that is, he wrote an article saying “you could do it this way.”

2. Why not use the machine's own name?

“An alias was a better alternative to 'pegasus.foo.com' which typically resulted when someone who happened to have a machine called pegasus started to run a web server...”

What he means is: in the early days, plenty of people just grabbed whatever machine was at hand — one called pegasus, say — and ran the Web on it, so visitors had to use pegasus.foo.com. That name meant nothing; users could not remember it, and they could not tell what it was for.

So he suggested giving it an alias, www, so that one glance told you it was a web server.

3. Why the three letters “www”?

Because the existing convention was already to name hosts after their service abbreviation: He was simply fitting the Web into that existing naming scheme. www was not chosen because it was special, but because it followed the same pattern as ftp and mail.

4. Why not just use the bare domain foo.com?

He gives two reasons:

“Typically early webmasters could not have comandeered the 'foo.com' address itself.”

Meaning: the bare domain foo.com is the “root identity” of the domain, usually controlled by the sysadmin, and the early Web people (webmasters) had no permission to change the DNS records of the bare domain. All they could do was add a subdomain within the area they could control.

“You don't have this flexibility of configuration if you point everyone at 'foo.com' itself for all services.”

The other reason is flexibility: with a www alias, if the web service grew later on, you could easily point www at a bigger machine without affecting the bare domain or the other services.

One Entertaining Detail

At the end of his answer, Tim says he is “of two minds about it now.”

Because by 1999, the Web had become the biggest service for many companies, and he thought maybe it was time to let the Web claim the bare domain. But he stresses at the same time: you can only pick one, you cannot run both as the main site, or your cache efficiency gets cut in half.

That is also in line with the idea in our next post, about why today's networks no longer use www and can just link to the bare domain instead.